Change underline phrase to show possession....

Did they sleep on the benches of the park?
benches of the park is what is underlined

Answer
Did they sleep on the park's benches?

Right

the bike of kobi was bought by his father

To change the underlined phrase "benches of the park" to show possession, you can use the possessive form of "park" by adding an apostrophe and an "s". The correct phrase would be "the park's benches."

So, the revised sentence would be:
"Did they sleep on the park's benches?"